fix(notifications): stop tick-wide row locks + poisoned-session swallows behind the PendingRollbackError 500s (#743)

* fix(notifications): release re-escalation row locks per row; stop swallowing DB errors in notify_get

The re-escalation sweep ran one tick-wide transaction, so each CAS
claim's row lock was held across every remaining delivery until the
single commit — a concurrent mark-read UPDATE on a claimed row starved
into the 60s lock_timeout. The sweep now commits per row (claim commit
releases the lock before delivery and makes the burned slot durable),
re-fetches each row by snapshotted id so one row's rollback can't
expire the rest of the tick, and savepoints each recipient's delivery.

notify_get's bare except swallowed the resulting LockNotAvailableError
into a false "notification not found" and returned a poisoned session
to the commit-at-send middleware, which blew up with
PendingRollbackError; it now catches only the two domain outcomes.

defer_after_commit's listeners fire on SAVEPOINT release too, which
would have drained deferred telegram/bus work before real durability —
they now skip savepoint boundaries via get_nested_transaction() (the
root get_transaction() is non-None inside the listener even at a real
commit). acknowledge_for_recipient's Redis dedup-clear moved before the
flush so the row lock never spans a Redis round-trip. The five
best-effort CEO-notify swallows that persist notification rows are
savepointed.

* fix(services): contain swallowed best-effort DB write failures instead of poisoning the session

Sweep of the same class as the notify_get incident: broad
except-Exception handlers that swallow a failure whose try-body writes
through the shared session leave the session rollback-pending, and the
verb/request then dies later with PendingRollbackError at
commit-at-send. Confirmed-dangerous sites now run the write inside a
savepoint (safe since defer_after_commit skips savepoint boundaries):
ceo_approve's verified-stamp, completion/pitch/postmortem-style CEO
notifies, _inherit_upstream_base, _link_commit_to_task (covers every
commit route), board-program LEARN records, the QA/PR-gate/PM-merge
verified-stamps, and the documenter->PM handoff.
_ack_pending_wake_notifications gets the same treatment so a wake-ack
failure can't fail the A2A read. telegram_inbound's per-update loop and
intake confirm roll back explicitly instead (their success paths commit
mid-flow, so a savepoint doesn't fit).

A swallowed savepoint rollback fully expires any ORM object mutated
inside the block, and the next attribute read raises MissingGreenlet —
strictly worse than the original bug. The two paths that keep using the
object after the swallow (doc handoff's envelope build, base
inheritance's claim continuation) refresh it in the except path;
regression tests run against a real session and were verified to fail
with the refresh reverted.

* test: shape mocked session.execute results so sync accessors stop leaking unawaited coroutines

An AsyncMock's auto-created children are themselves AsyncMock, so
production code that correctly awaits session.execute() and then calls
sync accessors (.scalars().all(), .scalar_one_or_none()) on the result
was silently collecting unawaited coroutines in 22 test files — 80
RuntimeWarnings per unit run, and in test_flow_soup_guard one mock
raised a real TypeError that a coincidentally-matching invalid_state
envelope masked. Each affected fixture now returns a plain MagicMock
shaped like a real Result. Zero AsyncMock warnings remain.

* docs: document per-row sweep commits and the savepoint/refresh containment pattern

---------

Co-authored-by: Renn F <rennf93@users.noreply.github.com>

tests/integration/test_a2a_service.py

@@ -43,7 +43,7 @@ from roboco.models.base import (
 from roboco.models.events import EventType
 from roboco.services.a2a import _LIVE_VIEW_EXCERPT_CHARS, A2AService
 from roboco.services.gateway.evidence_repo import EvidenceRepo
-from sqlalchemy import select
+from sqlalchemy import select, text
 from sqlalchemy import select as _sel
 from sqlalchemy.sql.dml import Update
 
@@ -2636,3 +2636,55 @@ async def test_read_a2a_acks_pending_wake_notification(a2a_setup: dict) -> None:
     refreshed = await db.get(NotificationTable, notif_id)
     assert refreshed is not None
     assert qa.id in refreshed.acked_by
+
+
+@pytest.mark.asyncio
+async def test_ack_pending_wake_notifications_savepoint_isolates_db_failure(
+    a2a_setup: dict,
+) -> None:
+    """A genuine Postgres-level failure inside `_ack_pending_wake_notifications`
+    (e.g. `bulk_acknowledge`'s flush hitting a lock timeout) must not poison
+    the shared session for whatever the caller does next. Force a REAL DB
+    error — not a bare Python exception, which alone never aborts the
+    underlying Postgres transaction — via a failing raw statement patched
+    into `bulk_acknowledge`, then prove the session is still usable
+    afterwards (no `PendingRollbackError`)."""
+    svc: A2AService = a2a_setup["svc"]
+    db = a2a_setup["db"]
+    qa = a2a_setup["qa"]
+    dev = a2a_setup["dev"]
+
+    notif = NotificationTable(
+        type=NotificationType.A2A_REQUEST,
+        priority=NotificationPriority.NORMAL,
+        from_agent=dev.id,
+        to_agents=[qa.id],
+        subject="A2A: ceo_dm",
+        body="pending wake",
+        requires_ack=True,
+    )
+    db.add(notif)
+    await db.flush()
+    notif_id = notif.id
+
+    async def _boom(_self: object, *_args: object, **_kwargs: object) -> None:
+        await db.execute(text("SELECT 1/0"))
+
+    with patch(
+        "roboco.services.notification_delivery.NotificationDeliveryService."
+        "bulk_acknowledge",
+        _boom,
+    ):
+        await svc._ack_pending_wake_notifications(qa.id)  # must not raise
+
+    # The savepoint rolled back the poisoned statement — the shared session
+    # is still usable for later work. Must be a real round trip (`.get()` on
+    # an already-identity-mapped, unexpired object would just return the
+    # cached instance without touching the DB, silently hiding a poisoned
+    # transaction) — `execute(select(...))` always issues the query.
+    refreshed = (
+        await db.execute(
+            select(NotificationTable).where(NotificationTable.id == notif_id)
+        )
+    ).scalar_one()
+    assert qa.id not in refreshed.acked_by  # the swallowed failure never acked

tests/integration/test_lifecycle_real_db.py

@@ -20,7 +20,7 @@ from __future__ import annotations
 
 from datetime import UTC, datetime
 from typing import TYPE_CHECKING, Any
-from unittest.mock import AsyncMock
+from unittest.mock import AsyncMock, MagicMock, patch
 from uuid import UUID, uuid4
 
 import pytest
@@ -653,6 +653,142 @@ async def test_doc_path(
     del cell_pm_agent  # asserted indirectly via cell_pm_for_team.
 
 
+@pytest.mark.asyncio
+async def test_doc_path_survives_handoff_failure_real_session(
+    db_session: AsyncSession, lifecycle_setup: dict[str, Any]
+) -> None:
+    """Round-2 regression (#doc-savepoint-expiry): _handoff_to_cell_pm's
+    `reassign()` mutates + flushes `t` inside the `begin_nested()` savepoint,
+    then `a2a.send` raises. On a REAL AsyncSession the savepoint rollback
+    fully expires every attribute of `t` — reading `t.status` /
+    `with_introspection(task=t, ...)` right after the except without
+    refreshing first raises `MissingGreenlet`, which propagates uncaught and
+    rolls back the WHOLE request (discarding the docs_complete transition the
+    warning claims survived). The equivalent unit test
+    (`test_i_documented_survives_handoff_failure`) mocks the session, so it
+    cannot reproduce this — a mock has no real ORM expiry semantics.
+    """
+    task = lifecycle_setup["task"]
+    doc_agent = lifecycle_setup["doc_agent"]
+
+    task.status = TaskStatus.AWAITING_DOCUMENTATION
+    task.pr_number = _PR_NUMBER
+    task.pr_url = _PR_URL
+    task.pr_created = True
+    task.qa_verified = True
+    task.assigned_to = None
+    task.commits = [
+        {"sha": uuid4().hex[:40], "message": "feat: /healthz", "task_id": str(task.id)}
+    ]
+    await db_session.flush()
+
+    task_service = TaskService(db_session)
+    # reassign() (a real write) runs BEFORE a2a.send inside _handoff_to_cell_pm
+    # — this raises only after that mutation has already flushed.
+    broken_a2a = AsyncMock()
+    broken_a2a.send.side_effect = RuntimeError("a2a down")
+    deps = ChoreographerDeps(
+        task=task_service,
+        work_session=_mock_work_session(),
+        git=_StubGit(db_session, task),
+        a2a=broken_a2a,
+        journal=_mock_journal_with_reflect(),
+        audit=AsyncMock(),
+        evidence_repo=_mock_evidence_repo(),
+    )
+    c = Choreographer(deps)
+
+    env = await c.claim_doc_task(doc_agent.id, task.id)
+    assert env.error is None, f"claim_doc_task failed: {env.message}"
+
+    env = await c.i_documented(
+        doc_agent.id,
+        task.id,
+        notes="Documented /healthz behaviour in docs/api/health.md",
+        files=["docs/api/health.md"],
+    )
+    body = env.as_dict()
+    # Must not 500 / propagate — this is the exact assertion that raises
+    # MissingGreenlet without the session.refresh(t) fix, since `status`
+    # reads `t.status` on the savepoint-expired object.
+    assert body["error"] is None, body
+    assert body.get("warning") is not None
+    assert "handoff" in body["warning"].lower()
+    assert body["status"] == Status.AWAITING_PM_REVIEW.value
+
+    final = await task_service.get(task.id)
+    assert final is not None
+    assert str(final.status) == Status.AWAITING_PM_REVIEW.value
+    assert final.docs_complete is True
+
+
+@pytest.mark.asyncio
+async def test_inherit_upstream_base_survives_flush_failure_real_session(
+    db_session: AsyncSession, lifecycle_setup: dict[str, Any]
+) -> None:
+    """Round-2 regression (#task-savepoint-expiry): the conflict branch
+    mutates `task` (the conflict marker + dev_notes) then `flush()`es inside
+    the `begin_nested()` savepoint. On a REAL AsyncSession a flush() failure
+    there rolls back the savepoint and fully expires every attribute of
+    `task` — the real caller (`claim_task_for_agent` ->
+    `_create_work_session_if_needed`) reads `task.project_id`/
+    `task.branch_name` right after this returns; `MissingGreenlet` is not an
+    `AttributeError`, so a `getattr` guard would not shield it, killing the
+    claim despite "never fails the claim". Forces a real, one-shot flush()
+    failure via monkeypatch — the closest realistic trigger to an actual DB
+    hiccup — mirroring `tests/unit/services/test_task_base_inheritance.py`'s
+    own project/git stubbing, but against a REAL session (that unit test's
+    mocked session cannot reproduce ORM expiry at all).
+    """
+    task = lifecycle_setup["task"]
+    project = lifecycle_setup["project"]
+    task.branch_name = "feature/backend/AAA--BBB"
+    await db_session.flush()
+
+    task_service = TaskService(db_session)
+
+    # Drive _inherit_upstream_base into the "conflict" branch (mutate +
+    # flush), mirroring the unit test's own project/git stubbing.
+    proj_svc = MagicMock()
+    proj_svc.get = AsyncMock(return_value=project)
+    git_svc = MagicMock()
+    git_svc.get_workspace = AsyncMock(return_value=MagicMock())
+    git_svc.merge_dependency_lineage = AsyncMock(
+        return_value={"status": "conflict", "files": ["a.py"]}
+    )
+    object.__setattr__(
+        task_service,
+        "_resolve_parent_branch",
+        AsyncMock(return_value="feature/main_pm/root"),
+    )
+
+    real_flush = db_session.flush
+    calls = {"n": 0}
+
+    async def _flush_once_boom() -> None:
+        calls["n"] += 1
+        if calls["n"] == 1:
+            raise RuntimeError("simulated flush failure")
+        await real_flush()
+
+    with (
+        patch(
+            "roboco.services.project.get_project_service",
+            MagicMock(return_value=proj_svc),
+        ),
+        patch("roboco.services.git.get_git_service", MagicMock(return_value=git_svc)),
+        patch.object(db_session, "flush", _flush_once_boom),
+    ):
+        await task_service._inherit_upstream_base(task, uuid4())  # must not raise
+
+    # `task` must be readable afterward — the exact access pattern
+    # `_create_work_session_if_needed` performs right after this call
+    # returns in the real claim flow. Raises MissingGreenlet without the
+    # session.refresh(task) fix in the except block.
+    assert task.project_id == project.id
+    assert task.branch_name == "feature/backend/AAA--BBB"
+
+
 # ---------------------------------------------------------------------------
 # 5. PM complete (Cell PM, simple task): awaiting_pm_review → completed
 # ---------------------------------------------------------------------------

tests/integration/test_notification_expiry_sweep.py

@@ -10,22 +10,104 @@ issues a real `expires_at < now()` query, so a mocked session (as
 
 from __future__ import annotations
 
+import asyncio
 from datetime import UTC, datetime, timedelta
 from typing import TYPE_CHECKING, cast
 from uuid import UUID, uuid4
 
 import pytest
+import pytest_asyncio
 from roboco.config import settings
 from roboco.db.tables import AgentTable, NotificationTable
 from roboco.models import AgentRole, AgentStatus, NotificationPriority, NotificationType
 from roboco.models.base import Team
 from roboco.models.notification import CreateNotificationParams
 from roboco.services.notification import NotificationService
-from roboco.services.notification_delivery import get_notification_delivery_service
-from sqlalchemy import select
+from roboco.services.notification_delivery import (
+    NotificationDeliveryService,
+    defer_after_commit,
+    get_notification_delivery_service,
+)
+from sqlalchemy import and_, delete, select
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
 
 if TYPE_CHECKING:
-    from sqlalchemy.ext.asyncio import AsyncSession
+    from collections.abc import AsyncIterator
+
+
+@pytest_asyncio.fixture(autouse=True)
+async def _committed_notification_senders(
+    _test_database_url: str,
+) -> AsyncIterator[list[UUID]]:
+    """Cleans up NotificationTable rows a test durably committed.
+
+    The sweep's per-row commit (#Correction 2) means a test that reaches
+    `sweep_expired_notifications` leaves its notification row(s) durable in
+    this session-scoped shared test DB — NOT teardown-rolled-back like
+    `db_session`'s own uncommitted work — which then pollutes a LATER test
+    file's system-wide notification listing (`test_notification_system_list`).
+
+    A test that commits appends its seeded sender agent id(s) to the yielded
+    list. A re-escalation row always inherits the ORIGINAL notification's
+    `from_agent` (see `_re_escalate_recipient`), so deleting every
+    NotificationTable row `from_agent`-matched to a test's sender(s) catches
+    both the original row and anything it spawned — the most precise handle
+    available, and it needs no separate tracking of recipient/target ids or
+    the re-escalation rows' own ids.
+
+    Runs on a wholly separate engine/connection (independent of `db_session`'s
+    own transaction state) so it always reaches Postgres regardless of what
+    `db_session` itself still has open when this fixture tears down.
+    """
+    sender_ids: list[UUID] = []
+    yield sender_ids
+    if not sender_ids:
+        return
+    engine = create_async_engine(_test_database_url, future=True)
+    try:
+        async with engine.begin() as conn:
+            await conn.execute(
+                delete(NotificationTable).where(
+                    NotificationTable.from_agent.in_(sender_ids)
+                )
+            )
+    finally:
+        await engine.dispose()
+
+
+async def _await_drain(session: AsyncSession) -> None:
+    """Await any `defer_after_commit` drain tasks stashed on the session
+    (mirrors `test_notification_delivery_phantom.py`'s helper) — the real
+    drain is fire-and-forget via `asyncio.create_task`, so a test must await
+    it explicitly rather than racing the event loop."""
+    tasks = list(session.info.get("_roboco_drain_tasks", []))
+    if tasks:
+        await asyncio.gather(*tasks, return_exceptions=True)
+
+
+async def _stale_unacked_count(session: AsyncSession) -> int:
+    """Mirrors `sweep_expired_notifications`'s own stale-unacked predicate.
+
+    The sweep's per-row commit (already true before this file's fixes —
+    see the `>= 1` assertions above) makes prior tests' rows durable in this
+    session-scoped shared test DB rather than teardown-rolled-back, so a new
+    test can't assert an exact sweep `count` — it must diff against this
+    baseline instead.
+    """
+    result = await session.execute(
+        select(NotificationTable).where(
+            and_(
+                NotificationTable.expires_at.is_not(None),
+                NotificationTable.expires_at < datetime.now(UTC),
+                NotificationTable.requires_ack.is_(True),
+            )
+        )
+    )
+    return sum(
+        1
+        for n in result.scalars().all()
+        if not NotificationDeliveryService._notification_is_fully_acked(n)
+    )
 
 
 async def _seed_agent(db: AsyncSession, *, role: AgentRole, slug: str) -> UUID:
@@ -50,6 +132,7 @@ async def _seed_agent(db: AsyncSession, *, role: AgentRole, slug: str) -> UUID:
 @pytest.mark.asyncio
 async def test_created_notification_expires_at_is_stamped_and_matched_by_sweep(
     db_session: AsyncSession,
+    _committed_notification_senders: list[UUID],
 ) -> None:
     """End-to-end: NotificationService._create_notification stamps expires_at
     for an ack-required row, and once that deadline is in the past,
@@ -63,6 +146,7 @@ async def test_created_notification_expires_at_is_stamped_and_matched_by_sweep(
     recipient = await _seed_agent(
         db_session, role=AgentRole.CELL_PM, slug=f"pm-{unique}"
     )
+    _committed_notification_senders.append(sender)
 
     svc = NotificationService()
     await svc._create_notification(
@@ -102,6 +186,7 @@ async def test_created_notification_expires_at_is_stamped_and_matched_by_sweep(
 @pytest.mark.asyncio
 async def test_directly_stamped_expired_row_is_matched_by_sweep_query(
     db_session: AsyncSession,
+    _committed_notification_senders: list[UUID],
 ) -> None:
     """Isolates the sweep query mechanics from creation: a hand-built
     ack-required, unacked row with expires_at in the past must be counted."""
@@ -110,6 +195,7 @@ async def test_directly_stamped_expired_row_is_matched_by_sweep_query(
         db_session, role=AgentRole.DEVELOPER, slug=f"s2-{unique}"
     )
     recipient = await _seed_agent(db_session, role=AgentRole.QA, slug=f"r2-{unique}")
+    _committed_notification_senders.append(sender)
 
     notification = NotificationTable(
         type=NotificationType.ALERT,
@@ -167,3 +253,297 @@ async def test_zero_ttl_disables_expires_at_stamping_end_to_end(
         )
     ).scalar_one()
     assert row.expires_at is None
+
+
+# =============================================================================
+# defer_after_commit vs. begin_nested() savepoints
+#
+# `_re_escalate_recipient` wraps `_persist_and_deliver` (which calls
+# `deliver()` -> `defer_bus_publish` -> `defer_after_commit`) in a
+# `begin_nested()` savepoint, per row, inside this very sweep. SQLAlchemy
+# dispatches `after_commit`/`after_rollback` on a SAVEPOINT release/rollback
+# too (verified live against this Postgres), so without the fix the pending
+# work would drain right there — before the sweep's own real per-row
+# `session.commit()` — reintroducing the phantom-notification bug the
+# outbox exists to prevent.
+# =============================================================================
+
+
+@pytest.mark.asyncio
+async def test_defer_after_commit_does_not_drain_at_savepoint_release(
+    db_session: AsyncSession,
+) -> None:
+    """A `begin_nested()` release must NOT drain pending work — only the
+    real root commit may."""
+    ran: list[str] = []
+
+    async def _work() -> None:
+        ran.append("ran")
+
+    defer_after_commit(db_session, _work)
+
+    async with db_session.begin_nested():
+        pass  # savepoint opens and releases; the root transaction stays open
+
+    await _await_drain(db_session)
+    assert ran == []  # not drained at the savepoint boundary
+
+    await db_session.commit()
+    await _await_drain(db_session)
+    assert ran == ["ran"]  # drained at the real root commit
+
+
+@pytest.mark.asyncio
+async def test_defer_after_commit_discarded_on_root_rollback(
+    db_session: AsyncSession,
+) -> None:
+    """A real root rollback discards pending work — no phantom event for
+    work whose enclosing transaction never became durable."""
+    await db_session.execute(select(1))  # force a real root txn to open
+
+    ran: list[str] = []
+
+    async def _work() -> None:
+        ran.append("ran")
+
+    defer_after_commit(db_session, _work)
+    await db_session.rollback()
+    await _await_drain(db_session)
+
+    assert ran == []
+
+
+# =============================================================================
+# Sweep per-row isolation (#Correction 1/2): one row's failure must not
+# corrupt or block another row's processing in the same tick, and a row
+# that does succeed must be durably committed regardless.
+# =============================================================================
+
+
+@pytest.mark.asyncio
+async def test_sweep_delivers_via_resolvable_chain_and_commit_is_durable(
+    db_session: AsyncSession,
+    monkeypatch: pytest.MonkeyPatch,
+    _test_database_url: str,
+    _committed_notification_senders: list[UUID],
+) -> None:
+    """The 3 tests above never seed a resolvable escalation chain, so
+    `_re_escalate_recipient` always short-circuits at `get_escalation_target`
+    returning None before ever reaching `_persist_and_deliver` — a due row's
+    real delivery path stays unexercised. Seed one row with a resolvable
+    chain plus a second row whose processing is forced to raise, and confirm
+    the first row really delivers (a new escalation NotificationTable row
+    addressed to the resolved target) and its `reescalation_count` bump is
+    durably committed — visible from a wholly separate connection, not just
+    this session's own (rollback-able) view — regardless of the other row's
+    failure.
+    """
+    unique = uuid4().hex[:8]
+    sender = await _seed_agent(
+        db_session, role=AgentRole.DEVELOPER, slug=f"snd-{unique}"
+    )
+    recipient = await _seed_agent(
+        db_session, role=AgentRole.CELL_PM, slug=f"rcp-{unique}"
+    )
+    target = await _seed_agent(db_session, role=AgentRole.MAIN_PM, slug=f"tgt-{unique}")
+    _committed_notification_senders.append(sender)
+    baseline = await _stale_unacked_count(db_session)
+
+    good = NotificationTable(
+        type=NotificationType.BLOCKER_ESCALATION,
+        priority=NotificationPriority.HIGH,
+        from_agent=sender,
+        to_agents=[recipient],
+        subject=f"good-{unique}",
+        body="body",
+        requires_ack=True,
+        expires_at=datetime.now(UTC) - timedelta(minutes=5),
+    )
+    bad = NotificationTable(
+        type=NotificationType.ALERT,
+        priority=NotificationPriority.HIGH,
+        from_agent=sender,
+        to_agents=[recipient],
+        subject=f"bad-{unique}",
+        body="body",
+        requires_ack=True,
+        expires_at=datetime.now(UTC) - timedelta(minutes=5),
+    )
+    db_session.add_all([good, bad])
+    await db_session.flush()
+    good_id = cast("UUID", good.id)
+    bad_id = cast("UUID", bad.id)
+
+    # This test only needs the escalation chain to resolve; who it resolves
+    # to doesn't depend on the recipient slug (real `ESCALATION_CHAIN` keys
+    # are fixed strings we can't safely reuse across tests without colliding
+    # on `agents.slug`'s uniqueness once the fix's per-row commit makes these
+    # rows durable rather than teardown-rolled-back).
+    monkeypatch.setattr(
+        "roboco.services.notification_delivery.get_escalation_target",
+        lambda _slug: f"tgt-{unique}",
+    )
+
+    # Fault-inject in `_re_escalate_unacked`, not `_maybe_reescalate` itself:
+    # the sweep has no ORDER BY, so whichever row it reaches first must not
+    # matter. `_maybe_reescalate`'s own CAS-claim commit runs BEFORE this
+    # call, so by the time "bad" raises, that commit has already flushed
+    # whatever was pending — including the initial insert of BOTH rows,
+    # which were only `flush()`-ed (not committed) before this sweep call.
+    # Raising any earlier (inside `_maybe_reescalate` itself, before its own
+    # commit) would let "bad" processed first roll back "good"'s still-
+    # uncommitted insert too — an order dependency, not a real assertion.
+    orig_re_escalate_unacked = NotificationDeliveryService._re_escalate_unacked
+
+    async def _re_escalate_unacked_one_fails(
+        self: NotificationDeliveryService, n: NotificationTable
+    ) -> int:
+        if n.id == bad_id:
+            raise RuntimeError("simulated processing failure")
+        return await orig_re_escalate_unacked(self, n)
+
+    monkeypatch.setattr(
+        NotificationDeliveryService,
+        "_re_escalate_unacked",
+        _re_escalate_unacked_one_fails,
+    )
+
+    deliv = get_notification_delivery_service(db_session)
+    count = await deliv.sweep_expired_notifications()
+    # Both new rows still counted as stale + unacked this tick, on top of
+    # whatever earlier tests in this session-scoped DB already committed.
+    assert count == baseline + 2
+
+    # Verify durability from a SEPARATE connection bound to the same test
+    # DB — proves the good row's commit really reached Postgres, not just
+    # this session's own still-mutable view.
+    verify_engine = create_async_engine(_test_database_url, future=True)
+    try:
+        verify_factory = async_sessionmaker(bind=verify_engine, class_=AsyncSession)
+        async with verify_factory() as verify_session:
+            good_row = (
+                await verify_session.execute(
+                    select(NotificationTable).where(NotificationTable.id == good_id)
+                )
+            ).scalar_one()
+            assert good_row.reescalation_count == 1
+            assert good_row.reescalation_delivered_count == 1
+
+            escalated = (
+                (
+                    await verify_session.execute(
+                        select(NotificationTable).where(
+                            NotificationTable.to_agents.contains([target])
+                        )
+                    )
+                )
+                .scalars()
+                .all()
+            )
+    finally:
+        await verify_engine.dispose()
+
+    assert any(f"good-{unique}" in (e.subject or "") for e in escalated)
+
+
+@pytest.mark.asyncio
+async def test_sweep_one_row_failure_does_not_block_the_other_rows_processing(
+    db_session: AsyncSession,
+    monkeypatch: pytest.MonkeyPatch,
+    _test_database_url: str,
+    _committed_notification_senders: list[UUID],
+) -> None:
+    """Before the fix, a root `rollback()` following one row's exception
+    expired every object still held from the earlier SELECT, so whichever
+    row `unacked` iterated to next raised `MissingGreenlet` on its own
+    attribute access (an async lazy-refresh attempted in a sync/greenlet
+    context) — aborting the whole tick instead of just skipping the bad row.
+    Snapshotting ids and re-fetching each row via `session.get` (async-safe
+    even post-expiry) makes every row's processing independent of any
+    earlier row's failure."""
+    unique = uuid4().hex[:8]
+    sender = await _seed_agent(db_session, role=AgentRole.DEVELOPER, slug=f"s-{unique}")
+    good_recipient = await _seed_agent(
+        db_session, role=AgentRole.QA, slug=f"gr-{unique}"
+    )
+    bad_recipient = await _seed_agent(
+        db_session, role=AgentRole.QA, slug=f"br-{unique}"
+    )
+    _committed_notification_senders.append(sender)
+    baseline = await _stale_unacked_count(db_session)
+
+    good = NotificationTable(
+        type=NotificationType.ALERT,
+        priority=NotificationPriority.HIGH,
+        from_agent=sender,
+        to_agents=[good_recipient],
+        subject=f"good-{unique}",
+        body="body",
+        requires_ack=True,
+        expires_at=datetime.now(UTC) - timedelta(minutes=5),
+    )
+    bad = NotificationTable(
+        type=NotificationType.ALERT,
+        priority=NotificationPriority.HIGH,
+        from_agent=sender,
+        to_agents=[bad_recipient],
+        subject=f"bad-{unique}",
+        body="body",
+        requires_ack=True,
+        expires_at=datetime.now(UTC) - timedelta(minutes=5),
+    )
+    db_session.add_all([good, bad])
+    await db_session.flush()
+    good_id = cast("UUID", good.id)
+    bad_id = cast("UUID", bad.id)
+
+    # No resolvable chain for either row — isolates this test to the
+    # row-isolation property alone (delivery-path coverage is the other test).
+    monkeypatch.setattr(
+        "roboco.services.notification_delivery.get_escalation_target",
+        lambda _slug: None,
+    )
+
+    orig_re_escalate_unacked = NotificationDeliveryService._re_escalate_unacked
+
+    async def _re_escalate_unacked_one_fails(
+        self: NotificationDeliveryService, n: NotificationTable
+    ) -> int:
+        if n.id == bad_id:
+            raise RuntimeError("simulated delivery failure")
+        return await orig_re_escalate_unacked(self, n)
+
+    monkeypatch.setattr(
+        NotificationDeliveryService,
+        "_re_escalate_unacked",
+        _re_escalate_unacked_one_fails,
+    )
+
+    deliv = get_notification_delivery_service(db_session)
+    count = await deliv.sweep_expired_notifications()
+    assert count == baseline + 2  # both new rows still stale + unacked
+
+    verify_engine = create_async_engine(_test_database_url, future=True)
+    try:
+        verify_factory = async_sessionmaker(bind=verify_engine, class_=AsyncSession)
+        async with verify_factory() as verify_session:
+            good_row = (
+                await verify_session.execute(
+                    select(NotificationTable).where(NotificationTable.id == good_id)
+                )
+            ).scalar_one()
+            bad_row = (
+                await verify_session.execute(
+                    select(NotificationTable).where(NotificationTable.id == bad_id)
+                )
+            ).scalar_one()
+    finally:
+        await verify_engine.dispose()
+
+    # The good row was fully processed (attempt slot claimed + committed)
+    # independent of whatever happened to the bad row.
+    assert good_row.reescalation_count == 1
+    # The bad row's CAS-claim commit (before the raise) is also durable —
+    # the raise happens in `_re_escalate_unacked`, strictly after that commit.
+    assert bad_row.reescalation_count == 1
+    assert bad_row.reescalation_delivered_count == 0